Audio signal processing system

1. An audio signal processing system including audio signal reproducing devices which respectively reproduce different sound contents in a plurality of areas including a predetermined area, said audio signal processing system further comprising: a receiving section which receives a plurality of audio signals having the different sound contents respectively; a process period specifying section which specifies a silent period in other audio signals except a particular audio signal for reproducing a sound content in the predetermined area that are received by the receiving section, respectively; a sound volume level adjusting section which decreases a sound volume level of the particular audio signal, in a period specified by the process period specifying section as a silent period in any of the other audio signals; and an outputting section which outputs the particular audio signal whose sound volume level is adjusted by the sound volume level adjusting section, wherein the different sound contents respectively include a contents identifier, and the audio signal processing system further comprises an identifying section that discriminates whether the received sound content is reproduced in the predetermined area or areas other than the predetermined area.

2. The audio signal processing system according to claim 1 , wherein the process period specifying section includes: a sound volume level sensing section which senses sound volume levels of the plurality of audio signals that are received by the receiving section; and a specifying section which specifies a period during which the sound volume level that is sensed by the sound volume level sensing section is below a predetermined level continuously in excess of a predetermined time, as the silent period.

3. The audio signal processing system according to claim 1 , wherein the process period specifying section includes: a sound volume level sensing section which senses sound volume levels of the plurality of audio signals that is received by the receiving section; and a specifying section which specifies a period during which the sound volume level that is sensed by the sound volume level sensing section exceeds a predetermined level as the non-silent period.

4. The audio signal processing system according to claim 1 , wherein the process period specifying section has a specifying section which receives data indicating silent periods attached to the plurality of audio signals, and specifies the silent periods of the plurality of audio signals from the data.

5. The audio signal processing system according to claim 1 , wherein the process period specifying section has a specifying section which receives data indicating non-silent periods attached to the plurality of audio signals, and specifies the non-silent periods of the plurality of audio signals from the data.

6. The audio signal processing system according to claim 1 , wherein the audio signal generating section includes: a frequency characteristic sensing section which senses frequency characteristic of the other audio signals; and a similar characteristic signal generating section which generates the second audio signal having a frequency characteristic that is similar to the frequency characteristic sensed by the frequency characteristic sensing section and that has a low similarity to the frequency characteristic of the particular audio signal.

7. The audio signal processing system according to claim 1 , wherein the audio signal generating section generates the second audio signal whose phase is opposite to phases of the other audio signals.

8. The audio signal processing system according to claim 1 , wherein the process period specifying section includes: a sound volume level sensing section which senses sound volume levels of the plurality of audio signals that is received by the receiving section; and a specifying section which specifies a period during which the sound volume level that is sensed by the sound volume level sensing section exceeds a predetermined level as the non-silent period.

9. The audio signal processing system according to claim 1 , wherein the process period specifying section has a specifying section which receives data indicating non-silent periods attached to the plurality of audio signals, and specifies the non-silent periods of the plurality of audio signals from the data.

10. The audio signal processing system according to claim 1 , wherein the plurality of audio signals received by the receiving section are radio audio signals and the radio audio signals respectively include an audio characteristic and content identifier.

11. An audio signal processing system including audio signal reproducing devices which respectively reproduce different sound contents in a plurality of areas including a predetermined area, said audio signal processing system further comprising: a receiving section which receives a plurality of audio signals having the different sound contents respectively; a process period specifying section which specifies a silent period in other audio signals except a particular audio signal for reproducing a sound content in the predetermined area that are received by the receiving section, respectively; a frequency characteristic correcting section which executes either a process of removing a predetermined frequency band component from the particular audio signal or a process of correcting the particular audio signal into an audio signal having a frequency characteristic that is similar to the other audio signals, in a period specified by the process period specifying section as the silent period in any of the other audio signals; and an outputting section which outputs the particular audio signal whose frequency characteristic is corrected by the frequency characteristic correcting section, wherein the different sound contents respectively include a contents identifier, and the audio signal processing system further comprises an identifying section that discriminates whether the received sound content is reproduced in the predetermined area or areas other than the predetermined area.

12. The audio signal processing system according to claim 11 , wherein the process period specifying section includes: a sound volume level sensing section which senses sound volume levels of the plurality of audio signals that are received by the receiving section; and a specifying section which specifies a period during which the sound volume level that is sensed by the sound volume level sensing section is below a predetermined level continuously in excess of a predetermined time, as the silent period.

13. The audio signal processing system according to claim 11 , wherein the process period specifying section has a specifying section which receives data indicating silent periods attached to the plurality of audio signals, and specifies the silent periods of the plurality of audio signals from the data.

14. The audio signal processing system according to claim 11 , wherein the plurality of audio signals received by the receiving section are radio audio signals and the radio audio signals respectively include an audio characteristic and content identifier.

15. An audio signal processing system including audio signal reproducing devices which respectively reproduce different sound contents in a plurality of areas including a predetermined area, said audio signal processing system further comprising: a receiving section which receives a plurality of audio signals having the different sound contents respectively; a process period specifying section which specifies a silent period in a particular audio signal received by the receiving section; an audio signal generating section which generates a second audio signal with respect to the particular audio signal, in a period specified by the process period specifying section as the silent period in the particular audio signal; and an outputting section which superposes the second audio signal on the particular audio signal to output a resultant audio signal, wherein the different sound contents respectively include a contents identifier, and the audio signal processing system further comprises an identifying section that discriminates whether the received sound content is reproduced in the predetermined area or areas other than the predetermined area.

16. The audio signal processing system according to claim 15 , wherein the audio signal generating section includes: a frequency characteristic sensing section which senses frequency characteristic of the other audio signals; and a similar characteristic signal generating section which generates the second audio signal having a frequency characteristic that is similar to the frequency characteristic sensed by the frequency characteristic sensing section and that has a low similarity to the frequency characteristic of the particular audio signal.

17. The audio signal processing system according to claim 15 , wherein the audio signal generating section generates the second audio signal whose phase is opposite to phases of the other audio signals.

18. The audio signal processing system according to claim 15 , wherein the process period specifying section includes: a sound volume level sensing section which senses sound volume levels of the plurality of audio signals that are received by the receiving section; and a specifying section which specifies a period during which the sound volume level that is sensed by the sound volume level sensing section is below a predetermined level continuously in excess of a predetermined time, as the silent period.

19. The audio signal processing system according to claim 15 , wherein the process period specifying section has a specifying section which receives data indicating silent periods attached to the plurality of audio signals, and specifies the silent periods of the plurality of audio signals from the data.

20. The audio signal processing system according to claim 15 , wherein the plurality of audio signals received by the receiving section are radio audio signals and the radio audio signals respectively include an audio characteristic and content identifier.